Starlin Castro Signing Only Raises More Questions

The Washington Nationals have had a busy winter. The defending champs had several departing free agents to negotiate with, and while they couldn’t hang on to Anthony Rendon, they had better luck with Stephen Strasburg, Howie Kendrick, and (as of two days ago) Asdrúbal Cabrera. Washington has also inked a few non-incumbents, most recently infielder Starlin Castro. Last Friday afternoon, the Nationals and Castro shook hands on a two-year agreement worth a total of $12 million. It’s a short-term contract for the (somehow only) 29-year-old, and there are no options or incentives to lengthen or sweeten the deal.

It feels like an eon since Castro debuted as a 20-year-old hit-tool wonder for the Cubs. At the time, the consensus on the Dominican was that, given his lack of power and solid glove at short, he’d have to hit .300 to be a good player. Initially, the projection held: In the early years of his career, he made All-Star teams when his average neared or crested .300 and was approximately replacement level when it didn’t.

But Castro’s post-Chicago tenure has played out a little differently. He slid over to second upon joining the Yankees in 2016, and has barely featured at short since. He’s also grown into more power with age, twice topping 20 homers in the last four seasons. That extra power has partially compensated for a dwindling average, and ultimately the overall value of his production hasn’t dipped too much even as its shape has shifted quite a bit.

Quietly toiling in obscurity down in Miami, Castro produced a strange season in 2019. Over the first three months of the campaign, he was one of the worst players in the league. At the All-Star break, he was running a .270 OBP with no pop, a bunch of double plays, and pretty much nothing good happening at the plate. Afterwards, matters improved significantly:

The big change is that Castro started hitting the ball in the air much more often: Castro ran a 52% groundball rate in the first half of the season, 43% in the second half. That’s not especially low in the aggregate, but over a full year, it’d be the lowest GB% (and highest FB%) of his career. As you’d expect, there was a mild but noticeable corresponding shift upward in his launch angle. He also started tugging the ball to left more often, which further helped facilitate an increase in power.

That’s all to the good, and it gives Castro a bit more upside than his modest salary suggests. Perhaps a number of teams ruing their infield options will come to regret eliminating all things Miami Marlins from their purview.

Still, we shouldn’t get too far ahead of ourselves. This isn’t the first time we’ve observed Castro tweak his swing and hit for more power over a stretch. Given his pedestrian exit velocity numbers, it’s unclear how helpful the additional fly balls will be if we get a deader baseball next season. And even in the player development era, we need more than a good half season before we overhaul our expectations for someone going forward. There’s always the possibility that he really has figured out to hit .300 with power, but it seems more likely that he’s the same streaky but competent hitter he’s been for years, likely to bat within sniffing distance of a 100 wRC+ on one side of the aisle or the other.

If that proves to be the case, this looks like a small bargain for Washington. The Nationals are paying one-win prices for a player who has averaged nearly 2 WAR annually over the last four years. Steamer projects 1.2 WAR for him next year, which seems a bit light, particularly if his strong second half augurs better production at the plate than the system can detect. Either way, there isn’t much downside with a $12 million commitment. If there’s even the slightest chance Castro has learned to hit for more power, the Nats stand to benefit in spades. Given Castro’s positional flexibility and durability, he’ll be handy to have around in any case.

More relevant than how he’ll play is whether this signals the end of Washington’s holiday shopping. With Castro in the fold, Cabrera and Kendrick back with the band, and top prospect Carter Kieboom primed for a promotion, Washington nominally has sufficient infield cover.

If nothing else, the positional versatility here is remarkable: Castro and Kendrick both made more than a dozen appearances at the hot corner, while Castro, Cabrera, and Kendrick have played plenty at second base in recent years. Kieboom, a shortstop by trade, started double-digit games at second, short, and third at Triple-A last year. This is a group short on players in their prime, but one that leaves Dave Martinez well-prepared to absorb an injury or an extended slump from a rookie. Where and how much everyone plays remains a question — for what it’s worth, Castro reportedly wants to play second — but the aforementioned four figure to handle most of the work at first, second, and third base. Steamer thinks it should be a cromulent crew:

It’s also a clear step down from last year. While Washington’s current infield looks decent on paper, the drop-off from Rendon to Castro and friends is substantial. Rendon was a seven-win player in 2019 and he topped 6 WAR in the two years before that. Even if the Nats get the good version of Castro, they’re still four wins worse than usual.

In that light, Washington’s continued interest in Josh Donaldson makes a lot of sense, even as his asking price seems to rise by the hour. The 34-year-old is the last elite player left on the market, and in a good year for free agents, he’s leveraging his position. Per recent reports, he’s seeking a four-year deal worth $100 million – a number free agents at his age can usually only dream of. But in a surprisingly competitive free agency period, the Nationals are just one of several teams interested in his services: The Twins have reportedly kicked the tires, and he’s also been linked with the Nats, Dodgers, Rangers, and Braves.

Perhaps Castro’s signing indicates that the Nationals are out of the Donaldson sweepstakes. He’d be a bit of a weird addition at this point; Washington has multiple above-replacement options at third, and adding another regular would muddle an already crowded picture. There’s also the inherent risk of committing nine figures to a player in his mid-30s to consider.

The Nationals should still be interested. Donaldson’s talented enough to shift the balance of power in the NL East by himself. If the Nats sign him, they upgrade by several wins while also ensuring that the reigning division champions enter 2020 a man down from last year. Ultimately, Castro’s arrival gives Washington cover if Donaldson chooses to play elsewhere. He’s a capable player with a dash of upside, and the Nats can certainly return to the playoffs with him in the lineup. But the Castro signing doesn’t preclude further activity; it only raises the stakes in what appears to be baseball’s tightest division.